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Results: Grayscale Tracking

HP ZR2740w Versus Asus PB278Q: QHD 27" Monitors, Tested
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All of the IPS panels that we’ve tested recently display excellent grayscale tracking, even at stock settings. It’s important that the color of white be consistently neutral at all light levels from darkest to brightest. Grayscale performance impacts color accuracy with regard to the secondary colors (cyan, magenta, and yellow). Since computer monitors typically have no color or tint adjustment, accurate grayscale is key.

HP ZR2740w

Since the HP has no RGB controls to adjust grayscale, we’re showing the measurement at a 200 cd/m2 brightness level.

This is a fair result. Grayscale error is visible from 30 percent to 100 percent, though just barely. The overall tint is cool in tone with just a hint of blue in white parts of the image. We ran this test at both minimum and maximum brightness settings and got nearly the same results. This is a good thing in that the HP achieves the same level of accuracy no matter what its light output.

Asus PB278Q

At its stock settings the PB278Q is deficient in green (a deficiency that increases as the signal level goes up). Bright images like the white background of a word processing app or Web browser look obviously blue. This measurement was taken in the User mode at the 6500K color temp preset. Standard mode looks the same as the above. sRGB mode is slightly better, though still blue in tone.

Fortunately, Asus includes RGB adjustments for both the high and low range, which is unusual for any computer monitor. This allows you dial in grayscale more precisely. Our procedure is to adjust the high range (gain) using an 80 percent signal and the low range (offset) using a 30 percent signal.

The extra adjustability allows a very accurate result in our grayscale tracking test. All the errors are now below two, except at 10 and 60 percent. In fact, most brightness levels are below one Delta E in this test. This is excellent performance.

Since most users lack the equipment to calibrate their monitors, out-of-box performance is important, especially in the grayscale metric. An error of over three Delta E is visible to the naked eye. Since most productivity apps have a white background, any tint can easily be seen.

The HP finishes third in this comparison. Its average grayscale error is barely visible. In fact, most people would not notice an issue. We used this monitor exclusively for several days and found it excellent for all types of content. The value of 3.26 Delta E was measured at the maximum brightness setting. The Asus comes in at the bottom of the default settings test. While not a grievous result, an instrumented calibration will improve the performance of the PB278Q greatly.

Here’s the line-up after calibration to 200 cd/m2.

The HP doesn’t really change when its brightness is reduced from over 400 cd/m2 to 200. This is a good thing since it shows consistency. The Asus looks great after calibration, and our measurements support this observation. Its grayscale performance is right there with the best screens we’ve tested. All of the monitors we’ve reviewed recently do extremely well in this test. In fact, many far more expensive consumer televisions don’t measure this well.

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  • 0 Hide
    KOKing , May 16, 2013 10:24 PM
    I've had one of these HPs at work for a couple of months (replacing an early 24" 1920x1200 IPS), which I've set fairly low), but as this review says, it's not really necessary. I was a little disappointed that, possibly because of the aspect ratio change to 16:9, it doesn't _feel_ like a lot more screen real estate.
  • -8 Hide
    Immoral Medic , May 16, 2013 11:13 PM
    Add 120hz, THEN it's enthusiast level.
  • -2 Hide
    bit_user , May 16, 2013 11:18 PM
    Where are all the OLED monitors? They should be cheap and plentiful, by now!
  • 8 Hide
    cangelini , May 16, 2013 11:59 PM
    SIDDHARTH MISHRAUseless review, the uniformity on these screens is pathetic, tried three of each, the color temp difference across the screen is over 1000K. Toms has very poor reviewers, only prad.de and overclockers.ru do reliable screen reviews. And btw the U2713HM is regularly on sale for $500 or so, the ZR2740W is now an overpriced relic lacking even an OSD.

    Screen uniformity is covered on page eight, and low points on both screens are discussed.
  • 0 Hide
    flong777 , May 17, 2013 2:03 AM
    Am I right by saying that the Asus monitor has more accurate color and better grayscale performance.
  • 2 Hide
    Marcus52 , May 17, 2013 2:07 AM
    Surprised that the Asus has slightly better lag results, as one of the reasons for not having an OSD is to reduce lag, and it can make a big difference. Of course, how you measure lag can get different results, and I've seen much lower numbers for the ZR2740w:

    http://www.tftcentral.co.uk/reviews/hp_zr2740w_v2.htm

    tftcentral is showing the HP as having far less lag than the Asus panel.
  • 4 Hide
    ceberle , May 17, 2013 5:07 AM
    The Asus certainly calibrates better than the HP; mainly because it can be calibrated. The HP is slightly better out of the box for grayscale and its chromaticity is also a touch better. Both screens have identical color to the eye. Only the instruments can tell the difference.

    Christian
  • 5 Hide
    ceberle , May 17, 2013 5:12 AM
    Regarding the lag results: It's hard to compare numbers from one review to another when the testing methods are so different. With our high-speed camera procedure, the only fair comparison is between the monitors we've tested. I would defend our response test as definitive though. Actually watching the screen draw in slow motion leaves no room for interpretation. The lag test is also consistent since we use the same signal chain for every screen. There is never a change in video cards, drivers, peripherals or any other device that might affect the result.

    Christian
  • 3 Hide
    dgingeri , May 17, 2013 7:22 AM
    I have the HP ZR2740w, and have for over a year now. It's a great looking monitor, and it performas well by my standards, but suffers from a significant lack of both reliability and support. HP's support is massively fragmented. It took me over three hours on the phone to get to the department that actually handled the support for this monitor. (It is a "Commercial" monitor, not business or personal. It's splitting hairs mighty thin, but that's the way HP's support is separated out.) When I finally got through, they sent a tech with a replacement monitor the next day. However, it also has two major hardware issues that render it useless when they occur. Most of the first run monitors had the power supplies die within months. The second run monitors had a serious issue with the control boards. All of them have issues with the USB hub, but it least the monitor keeps working if you don't have the USB cable plugged in. As an owner of one, I would not, under any circumstances, recommend this monitor to anyone.

    HP: the perfect example of a company falling apart because it is both too big and too fragmented.
  • 0 Hide
    ubercake , May 17, 2013 8:42 AM
    Does anyone know how absolute input lag of the IPS monitors compares with that of higher end TN-panel monitors?
  • -1 Hide
    maxinexus , May 17, 2013 9:02 AM
    Who cares about 1440p...where are the 4k gee how long does it going to take!!!
  • 1 Hide
    sempifi99 , May 17, 2013 9:52 AM
    I have had this HP monitor for about 2 years now. It is a good and solid monitor. It turns on in a matter of seconds and the 12 ms response time is not a problem at all. Though I do wish it was a bit quicker, but you can not have everything at this price point. Also, there is software calibration to adjust the color output so the lack of monitor adjustment did not bother me at all.


    What I don't understand is the difference of input lag compared to other reviews. The Acer has been measured at 16.6 ms while the HP is an amazing 3.6 ms with a CRT being used as the zero set point. I am not sure the exact toms hardware testing methodology but it seems to synthetic, not representing real world performance.
  • 0 Hide
    ceberle , May 17, 2013 12:56 PM
    The testing procedure is explained in the review. We shoot video at 1000 fps of a black to white screen draw. Then we simply count the number of frames it takes for the white field to fill the screen. The input lag is measured the same way. The video shows the pattern generator's lights flashing when the signal is sent to the monitor. We count the frames between the flash and the full rendering of the pattern to arrive at the input lag measurement. We do this five times and average the results.
    -Christian
  • -1 Hide
    Nintendo Maniac 64 , May 17, 2013 1:35 PM
    So I guess I'm the only one interested in a monitor's upscaling quality? I mean, we don't always play the latest AAA games - I myself like to play some Touhou from time to time, but it's locked to a 640x480 window which is pretty tiny on a high-res display. That leaves you with fullscreen which puts you at the mercy of your monitor's and/or GPU's upscaling ability.
  • 0 Hide
    Anonymous , May 17, 2013 2:24 PM
    Hp when oh when are you going to make a 30 inch 2560 x 1600 led or oled display or better yet a 4K ready version at 30 inches or better??
  • 1 Hide
    Spooderman , May 17, 2013 5:17 PM
    Considering the cost of such a panel, probably not for the next 5 or so years.
    soldier2013Hp when oh when are you going to make a 30 inch 2560 x 1600 led or oled display or better yet a 4K ready version at 30 inches or better??

  • 0 Hide
    mczak1 , May 17, 2013 8:43 PM
    No workaround for other resolutions? Seriously? Last time I checked gpus had output scalers (since about 15 years or so...). Maybe you need to activate it manually if the driver can't figure out the monitor can do scaling on its own but pretty sure it should work...
  • 1 Hide
    agnickolov , May 17, 2013 10:54 PM
    Quote:
    With UHD (Ultra HD, 4K, or 2160p) just around the corner, QHD represents the highest pixel count that you can put on your desktop right now.

    Technically, there's also 2880x1800, but it's only on iMac-s so far. Still, the panels exist...
  • 0 Hide
    MasterMace , May 17, 2013 11:46 PM
    1440 and 1600p are now old. 2160p is where it's at :) 
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